Wanted to clarify and detail the same problem listed originally by neil3646 and also by the quoted poster above (among others).
I've have had this issue for for a few weeks now. It first seemed to occur randomly during career mode daily/weekly stages and rallycross events. You'd complete the stage, hit continue, and the game would lock up, and shortly there after kick you to the dashboard. It seemed to be random at first, affecting some events, but not all. This would sometimes happen in a single event, but also could happen after completing a single stage in a weekly or monthly event.
More recently (last week) I found that I was getting booted to the dash just trying to load into a stage or enter career mode would close out the game and send me back to the dash. I found a way around that by first playing a historic event rally, completing one stage, exiting back to the main screen and then going back into career mode for the dailies. I could still experience a random crash after completing a single stage however.
Now with the Flat out Pack, I have the same random issues of crashing in the daily/weekly events, but I cannot even start the Colin McRae Challenges. I'm immediately kicked back to the XBox dashboard upon selecting 'start event'.
I'm playing on a standard Xbox One, playing with a standard controller. I've been playing Dirt Rally 2.0 since launch on the same setup. I am signed in to RaceNet for during all these issues. I've tried on Medium and Very Easy difficulties to load the McRae Challenges, but with the same results.